Occasionally in the surgical practice of human and veterinary medicine, it is desirable to impair or halt the fuction performed by a bodily tissue member such as a linear ligament or tubular organ. Typically, this is done by severing, ligating, shortening or occluding the structure of the bodily member. In one of the more common methods, electrocoagulation, an instrument is inserted into the body cavity through a small incision and heat is applied to the organ, in situ, until the tissue burns and is severed or, if a tubular organ, its passageway occluded. Obstruction of a surgeon's view by the smallness of the incision and the proximity of other bodily members however, creates a risk that a member other than the one intended will be inadvertently injured by cauterization or perforated by the instrument, perhaps without the surgeon's awareness.
Another method, occasionally used to occlude elongated tubular organ structures, relies upon a small, three-piece clip. A small incision is made in the wall of the body cavity and an applicator holding the clip in its distal end is inserted into the cavity. The applicator is manipulated to apply the clip across the tubular organ in situ. A small bias spring slips over the ends of the arms of the clip to lock the clip into a closed position so that sharp teeth on the opposite ends of the arms penetrate and firmly grasp the tubular structure. The locking action of the spring causes the arms to compress and occlude a cross-section of the tubular structure. The necessary rigidity of the arms of a clip of this type means that the size of a clip must be carefully tailored to the dimensions of the tubular structure. If too small, a clip will fail to completely engage the structure, and will, therefore, cause only a partial occlusion. If too large, the clip will present a hazard to neighboring organs. Furthermore, if a clip is applied obliquely to the length of the tubular structure, it will likely fail to cause a complete occlusion and thus render the operation a failure unless the oblique application is immediately discovered. If discovered, however, an obliquely applied clip cannot be easily removed due to the locking action of its bias spring. Consequently, the applicator must be removed through the incision, loaded with a second clip, and re-inserted to correctly apply the second clip to the tubular structure. Occasionally, it may be necessary to repeat these steps several times before one clip is successfully applied so as to completely occlude the passageway inside the tubular structure. Another difficulty arises from the propensity of these small clips to fall out of the applicator before its bias spring is fully engaged, thus permitting the clip to freely tumble about within the body cavity. Unless promptly located and retrieved, the sharp teeth of the open clip will likely injure and possibly, penetrate, an unintended organ or structure.
The Pomeroy technique, another common method, is an open laparotomy procedure often used for tubular ligation that requires a larger incision to be made in the wall of a body cavity. The bodily tissue member to be operated upon is manually pulled out of the cavity through the incision and drawn into a loop or band, forming a knuckle. The loop is ligated by tying it with catgut. If the loop is part of an elongated tissue organ, the tightness of the catgut ligature occludes the passageway inside the tubular structure. The knuckle, that is, the proximal end of the loop is then cut off and taken to a pathological laboratory for identification. The large size of the required incision and concomintant inconvenience of the patient, a long hospital stay, a high incidence of infection, and an unnecessarily large scar are particular disadvantages of this method.
Although the Pomeroy technique is the most accepted and popular method, the introduction of the endoscope into general surgery and the field of gynecology permits a Pomeroy-like technique to be utilized through an endoscope (laprascope) ring applicator. In this Pomeroy-like technique, a much smaller incision is made in the body cavity wall to permit insertion of a multi-cylinder laparoscopic applicator bearing a small elastic ring stretched over its distal end. Forceps extending out of an operating channel inside the applicator completely grasp a cross-section of a linear organ structure such as a Fallopian tube or round ligament. When retracted, the forceps draw the linear organ structure into a loop with the knuckle of the loop pulled into the operating channel of the applicator. Further manipulation of the applicator causes relative movement of two applicator cylinders, ultimately forcing the elastic ring over the mid-section of the loop, thereby completely and automatically occluding the tubular structure. The loop is then released and the applicator withdrawn. Although this method is comparatively quick, simple and reliable, if the loop is not of sufficient size, it is possible for the ring to slip over the knuckle, thereby releasing the loop from occlusion. This may also happen even with a loop of adequate size, if the occluded bodily member is subsequently subjected to vigorous physical motion (e.g. pelvic examination) before fibrosis of the ring occurs.
In all of the presently used methods for severing, ligating or occluding the structure of a bodily tissue member, it is quite possible to inadvertently operate upon the wrong organ or structure. This is particularly likely in a method where the surgeon's field of view is either limited by the minuteness of the incision or constructed to the image provided by an endoscope. For example, in a laparoscopic tubal sterilization of a human female, it is possible to mistakenly grasp and occlude either the round ligament or the ovarian ligament, or even a bowel structure rather than a Fallopian tube. Discovery of inadvertent occlusion of the wrong structure may be delayed by a period of days or longer, until the patient's discomfort or bodily malfunction necessitates further surgery.
An additional disadvantage of presently used methods lies in the frequency with which the bodily member to be operated upon is unusually oversize, either due to natural causes or to infection. Unless its size is detected during surgery, any attempt to ligate or occlude the member via a small incision technique will likely fail due to either the inadequate size of the occluding device or the smallness of the operating channel of the applicator.